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Question re Orangethroat vs Rainbow Darter


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#1 DaveW

DaveW
  • NANFA Member

Posted 31 August 2019 - 11:49 AM

Hi all,

 

Is it reliable that Orangethroats have an all-blue anal fin without any red or orange spot?

 

And that Rainbows lack skimpy horizontal rows of dark spots on the upper sides not far behind the gills?

 

I've got some darters from Union Co., Illinois, that seem to be Rainbows, as the body depth is greatest below the 1st dorsal fin rather than in front of it, and they have large red/orange areas on the partly blue anal fin, so those traits are good for a Rainbow.

 

But they do have a few small dark flecks in more or less horizontal array, on the upper part of the forward part of the body, which is supposed to be an Orangethroat trait. I suspect that I shouldn't let these bother me, as the other things seem to say "Rainbow".

 

Any thoughts?



#2 Doug_Dame

Doug_Dame
  • NANFA Member

Posted 31 August 2019 - 01:50 PM

My first thought is "Photos are useful !" 


Doug Dame

Floridian now back in Florida
 


#3 JasonL

JasonL
  • NANFA Member
  • Kentucky

Posted 01 September 2019 - 08:23 AM

I have found the orange/red anal fin coloration to be a reliable feature for E. caeruleum. Rainbows don't HAVE to have this but if you find a fish that does its a pretty good bet it's not E. spectabile.

Rainbows also have the horizontal dark rows of dots but they are not nearly as prominent or linear in appearance as I've seen in orangethroats. Seems to be more visible in juvenile or female rainbows in my experience.

Union County IL has both species. If you post a pic I bet we could figure it out.

#4 Fleendar the Magnificent

Fleendar the Magnificent
  • NANFA Member
  • Ohio

Posted 02 September 2019 - 02:34 PM

So far, every rainbow darter I've caught and have in my tank has had the red/blue anal fin coloration whereas the orangethroat darter doesn't. However, it wouldn't surprise me if evolution hasn't thrown a bit of a curveball and you might see an orangethroat with red on the anal fin and a rainbow without. We have both species here in Ohio, but the orangethroat's range is more northwestern of my central location and I have scads of rainbows.

 

Chris M.



#5 BenCantrell

BenCantrell
  • Moderator
  • San Diego, CA

Posted 03 September 2019 - 02:55 PM

Hutchins Creek has hybrids between the two, so keep that in mind if that's where you were.






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